Why is my ex acting this way?

Why would my ex girlfriend be mad at me and show jealousy when I told her I was seeing someone? She left me for her current boyfriend. She is trying to rub it in my face how happy she is with her current boyfriend.

Updates:

It's been 5 months since the BU and this was our first time talking in 2 months. Her emotions towards me are all over the place.

There's several reasons. It could be as innocent as she isn't over her feelings for you or the worst...she wants to keep control over you in that she can do what she wants, but you can't move on and be happy without her. Either way, some people cannot be friends with their exes, so maybe it's best that you break off communication and move on. You have every right to pursue happiness with someone else just as she does.

What Guys Said 2

is she really rubbing it in your face or just talking about it? and you feel like it's rubbing in your face?

As far as why she is acting jealous? she's probably finding it hard to think of you with another person the same way you find it hard to hear about her with another guy.

basically I think you two should still keep a bit of distance cause it sounds like you are both not entirely over the relationship you had to the point where you can be together without feeling emotions of jealousy or whatever